This project focuses on the interactions between experience and adult neurogenesis in the hippocampal region of the brain. We are interested in understanding how experiences, including learning or stressful experiences, regulate adult neurogenesis and how the new neurons alter responses to stress and learning situations. We study the regulation and function of adult neurogenesis in rats and mice, which show continued production of new neurons throughout adulthood similar to that in primates, including humans. We have previously found that specifically inhibiting adult neurogenesis in mice increases their hormonal and behavioral responses to stress, increasing depressive-like behavior. During the past year, we have focused on identifying behaviors that are altered when adult neurogenesis in inhibited using pharmacogenetic manipulations in mice or rats. We have investigated the role of new neurons in stress-mediated changes in hippocampal structure and in behaviors that are associated with stress, including defensive behaviors and consumption of highly rewarding food/drink.